I'd replace the on/off switch to be safe, and be sure to do a range check before you try to fly with that receiver again, but it's likely that it's okay.

1.2 mA's IS 2C for the 600 mAH pack, and it should have been a safe charge, but as FH mentioned in his last post, a peak detect charger will reduce the likelyhood of an overcharge, but not prevent it.

Re-charging too soon was probably what caused your problem, because the closer the pack is to fully charged, the less likely the charger is to see the peak, and the less expensive the charger the more likely it will also be to miss the peak.

Sorry about your pack, but it was a relatively cheap lesson.
Dennis-