Rotated tires--now balancing issues

[Boss Hoss]

Heres the deal: Bought my tires and rims from an online source and they werent balanced correctly. It wasnt bad just a little wiggle in my steering wheel. After presenting this to the board i decide to go get them balanced. Bring them to a local truck shop and they say i must pay for all 4 to make sure they are balanced correctly....not a problem as $25/tire to preserve my front end and stop the shakes is not a big deal. Get it back fromt he shop rides smooth as glass. Great right? Well i recently rotated my tires(directional tire so fronts go to back, back to front) and guess what? Shake is back in the steering wheel. Directly before rotating them balancing was perfect. As soon as i drive my truck after the balancing shakedy shakedy!

I dare say the truck shop just balanced the front. Would anyone agree this is a safe assumption?