If you have had no other problems with this pistol except an average of one FTE every 900rd., and are shooting cheapo stuff through it sometimes, I would not worry too much, especially since two of them were from the same 100rd. of Remington...if your memory is good. Eliminate that 100rd. (Remington's QC is very spotty with their yellow box stuff, some, at least, is made in Mexico) and you have three FTE's in 4400 rd...one in about every 1470rd. There is so much that can happen, from a bad round to a dirty chamber, to lack of lube at the end of a long shooting session, etc. etc. that "could" cause this, I do not really believe it is diagnosable in any realistic manner, nor do I believe it is any sort of a problem to be concerned about.
Go enjoy your gun.