Parts printing with outward draft at base

[soofle616]

Hopefully someone has had a similar issue and can point me in the right direction. ABS prints on FF creator pro, 230/110 nozzle/bed temp. Every print I run ends up with an outward draft from the base for the first 2.5-3mm. The fist layer appears to get laid down just fine but ends up being undersized in both directions. Subsequent layers get wider and wider until I finally get to the intended width of the part. This has been going on since the first part I printed (calibration cube) but most of what I've done so far hasn't had much in the way of vertical sides so it hasn't been all that noticeable. Are the first few layers shrinking more than what comes after them for some reason? Is it a problem with the feeds/speeds I'm using? It doesn't seem to matter what software I use to send the build, both replicatorG and makerware have resulted in the same thing.

The more I think about it though, it does seem to happen only when printing over USB. I've run two parts with vertical sides off the SD card and both came out nice and square. Is it a usb communications issue? I don't have time today to run another print from the SD card and see what happens so I'll do that tomorrow morning and report back but any suggestions would be appreciated. This has occurred at .1 and .2mm vertical steps and with different shell counts and infill percentages.