Can't figure out why LiveCycle text fields are not expanding

Just started using LC E4, I followed a simple tutorial for form flow, but when I preview the PDF, the text field does not expand.  I have the field set for Allow Multiple lines and Allow for Page breaks within Content, but when I type more than one line, I get the scroll bar, not an expanded field.  I tried saving as a dynamic pdf and then re-open...same problem.  Any idea what I'm missing?