Can Header Bolts be too tight???

[BigRed]

I have a set of Dynomax ceramic coated header that have been on since September. I have the typical problem of bolts loosening up over time and I have to tighten them back due to small leaks.

A couple days ago I tightened my bolts down due to a small leak and for some reason I still have a leak on the driver's side.

Is it possible to tighten these bolts too much and warp the flange? As I said, the headers are fairly new and I've only retightened them twice. I installed the gaskets that came with the headers (FelPro) and did NOT use locking bolts. At the time I bought my exhaust system, I didn't have the extra $40.

Thanks in advance...