MX - Dynamic Text Box Positioning

I have 2 dynamic text fields instance names textField1 & 2, drawing their content from a text file containing 2 variables (text). Both text fields are set to autosize, so they change in width according to the amount of characters in the variable.
I also have the following code to position text field 2 to the right of text field 1

textField2._x = textField1._x + textField1._width + 10;
textField2._y = textField1._y;

When the textfield is static, it works fine. However, using dynamic text seems to be a problem and the right field just displays 5 pixels from the left x position of text field 1… I think the problem is the way i’ve set up the script - it doesn’t appear to recognise the width of textfield 1 as set by the autosize command.
If anyone can help I’d be very much obliged.