It's been a long time since I did a valve grind, but shouldn't a good machine shop trim the valve stems to compensate?
Shoulda, woulda, coulda! My favorite three words.
Talk directly with the shop that did your heads and get them to put in writing exactly what they did. If they shaved the heads and/or block together more than 10 thou, tell them that you are concerned about valve clearance and want them to guarantess you won't ahve issues. If they won't guarantee it as is, ask them what they will do to guarantee it.
1) grind the valve stems down which may not be the best option.
2) obtain shorter push rods to compensate for the grinding.