Sprites are moving when they shouldn't?

(Yes, I'm making a sprite-based game. Don't ask why.)

local label = script.Parent
local RunService = game:GetService("RunService")
local Debris = game:GetService("Debris")
local length = label:WaitForChild("Length")
local width = label:WaitForChild("Width")
local angle = label:WaitForChild("Angle")
local delaytime = label:WaitForChild("Delay")
local life = label:WaitForChild("Lifetime")
local t = label:WaitForChild("Transparency")

local delayLine = Instance.new("Frame")
delayLine.Parent = label
delayLine.Name = "DelayLine"
delayLine.Size = UDim2.new(0, 1, length.Value, 0)
delayLine.AnchorPoint = Vector2.new(0, 0)
delayLine.BorderSizePixel = 0
delayLine.BackgroundColor3 = Color3.fromRGB(255, 255, 255)
delayLine.BackgroundTransparency = 0.5
delayLine.Position = UDim2.new(0, 0, 0, 0)

local hitbox = Instance.new("Frame")
hitbox.Parent = label
hitbox.AnchorPoint = Vector2.new(0.5, 0.5)
hitbox.Size = UDim2.new(0.33, 0, 1, 0)
hitbox.Position = UDim2.new(0.5, 0, 0.5, 0)
hitbox.BackgroundTransparency = 1

local hitboxScript = game.ReplicatedStorage.BulletScripts:WaitForChild("LinearHitboxScript"):Clone()
hitboxScript.Parent = hitbox
hitboxScript.Disabled = true

delay(delaytime.Value, function()
    label:TweenSize(UDim2.new(0, width.Value, 0, length.Value), "Out", "Quad", 0.25, false, function()
        Debris:AddItem(label, life.Value)
    end)
end)

function getRealAngle(a)
    local val = math.abs(a - 180)

    if a > 180 then
        val = val * -1
    end

    return val
end

label:GetPropertyChangedSignal("Size"):Connect(function()
    if label.Size == UDim2.new(0, 1, 0, 1) then
        delayLine.Visible = true
        label.ImageTransparency = 1
        hitboxScript.Disabled = true
    else
        delayLine.Visible = false
        label.ImageTransparency = t.Value
        hitboxScript.Disabled = false
    end
end)

RunService.RenderStepped:Connect(function()
    label.Rotation = getRealAngle(angle.Value)
end)

When the sprite is created, its size is set to UDim2.new(0, 1, 0, 1). After a certain amount of time passes, the sprite expands to its true size, determined by the values of Length and Width.

However, when the sprite's size changes, it moves towards the bottom of the screen, even though I don't have anything that changes the position in the script. Is there a way to fix it?

Here's the function that creates these sprites, in case it helps with figuring out the problem:

function lib:CreateStraightLaser(x, y, angle, length, width, delaytime, graphic, timer)
    local RealLaser = getShotData(graphic)
    local BoundBox = RealLaser.Bound
    local sLaserScript = ExtraScriptsDirectory:WaitForChild("StraightLaserScript")

    local sLaser = Instance.new("ImageLabel")
    sLaser.Name = RealLaser.Name
    sLaser.Position = UDim2.new(0, x, 0, y)
    sLaser.Size = UDim2.new(0, 1, 0, 1)
    sLaser.AnchorPoint = Vector2.new(0.5, 0)
    sLaser.BackgroundTransparency = 1
    sLaser.Image = ShotSheetImage
    sLaser.ImageRectOffset = BoundBox.Min
    sLaser.ImageRectSize = Vector2.new(BoundBox.Width, BoundBox.Height)
    sLaser.ImageTransparency = 1

    local l = Instance.new("NumberValue")
    l.Parent = sLaser
    l.Name = "Length"
    l.Value = length

    local a = Instance.new("NumberValue")
    a.Parent = sLaser
    a.Name = "Angle"
    a.Value = angle

    local w = Instance.new("NumberValue")
    w.Parent = sLaser
    w.Name = "Width"
    w.Value = width

    local d = Instance.new("NumberValue")
    d.Parent = sLaser
    d.Name = "Delay"
    d.Value = delaytime

    local life = Instance.new("NumberValue")
    life.Parent = sLaser
    life.Name = "Lifetime"
    life.Value = timer

    local t = Instance.new("NumberValue")
    t.Parent = sLaser
    t.Name = "Transparency"
    t.Value = RealLaser.Transparency

    local newLaserScript = sLaserScript:Clone()
    newLaserScript.Parent = sLaser
    newLaserScript.Disabled = false

    sLaser.Parent = getLocalPlayerGui()

    return sLaser
end