New roof gone weird....

[LOCKr]

Hi, Having needed a new roof I contacted a friend whos son is a roofer. Got an estimate and also set up my neighbor with the guy to do his roof. We got them both done with the same type of shingles,just different colors. After a couple of weeks,my neighbors roof developed spaces in between sections of shingles and in one case a space of about 3/4 of an inch the whole length of the roof in the middle of the pitch. Well,after some choice words from my neighbor about my friends son and threats of law suits, the roofer did show up and removed the whole half of the roof and repalced it. Now at this point I was satisfied with my roof as I couldn't see any problems but there is one side of the roof I cannot see from my yard and the wife noticed today that it looked like the same situation as my neighbor had. Lifted shingles. Anyone out there ever experiance this.Is it common and what would attribte to this lifting? I'll be on the phone tomororw!