It's fine, just let it go. The only thing I can imagine is on your original hammer the half cocked ramp had worn down a bit and this isn't the case on the new hammer and/or they were a little "rough" with your sear spring and gave it some more pressure.
Either way, it'll be absolutely fine just pulling the trigger and letting the hammer go on it's own. The hammer impacts the knocker which is spring loaded, we're talking about the tiniest amount of wear/impact to the hammer ever. It'll take it a million times (well maybe not if it's Vorsk) before it breaks.
Just remember - there is no firing pin, there is no "chamber" it's an airsoft toy, normal gun physics and logic don't apply as much.