[Sure Shot Mc Gee]

I think you may have a few things going that may be the cause of your problem.

but the weird thing is this was way under the max load.

49.0 grs of imr 4831 is way below any powder listings that I'm aware of. Your cartridge could be building to much internal pressure because of using too little amount of a slow burning powder.

The load was 49 grains of IMR 4381 an a Hornady 150 grain SP bullet which is a mid range load according to their manual.

Who's manual are your referring too Sir?
My Speer #11 says 55.0 to 59.0 for imr-4831 and using 150 gr. bullet
again my older Hornady 3rd edition stat's are:
56.9 to 60.3 for the same.

Something really unusual.
IMR's Powder booklet and Hodgdon's web site doesn't even suggest IMR-4831 being used for your bullet weight.

And if using Varget it's suggested by IMR's web site to be measured:
47.0 to 51.0 and using a 150 gr. bullet.

I did seat it a little longer than what the load data listed.

I would also suggest to seat your bullet to what is considered the proper OAL for any caliber. The stat's for your 30-06 are:
Min: 2.970 Max: 3.340

Shorting powder measurements and extended bullet length preformed on a 30-06 cartridge. I highly doubt your gain all that much tighter groupings. If indeed looking for a little additional accuracy I encourage you to try Neck sizing instead. You may see some improvement in your rifles groupings then

S/S