The first Glock 22 models were built on the Gen2 frame (deep checkering on front and rear of grip-frame, stippling on the sides, but no finger-grooves or thumb-rest depression). Early G22 models will also have a flat-sided extractor on the slide (vs. the notched Loaded Chamber Indicator (LCI) extractor on current models); the caliber marking on the slide may read ".40 SW" (vs. just ".40" on current models); the frame dust cover will be smooth (newer models have a dust cover accessory rail for lights, etc.); and the magazines are probably non-fully-metal-lined (NFML, vs. FML/fully-metal-lined, to prevent excessive swelling of the magazine when full and to allow it to drop free of the weapon when the mag release is pressed, for quicker reloads).
Some early .40 caliber Glocks had rather generous chambers, which can contribute to bulging cases during firing (or bursting cases, in a worst-case scenario). Worst-case. Heh.
If it functions well, then the only thing I'd recommend is upgrading to the current generation of magazines; the new mags are much better at feeding JHP ammo than the old mags, and will eject more smoothly for fast reloads.
If you are having functioning difficulties with it, then I'd recommend sending it back to Glock with a description of the problem(s), and they will most probably fix it for free.
To compare frame generations, check the photo in this thread:
Glock frame identification, or, "What generation is my Glock?"