New Text Message "GLASS" sound issue

I noticed with my 3G iPhone and now also with my 3G[s] that if I choose the GLASS tone as my New Text Message Tone, if I put the vibrate switch to vibrate and then switch it back so the sound is on, my phone doesn't make the GLASS tone if I receive a new text message... it still only vibrates as if my phone is set to vibrate. The only thing that makes the GLASS tone start working again is if I turn the phone completely off and back on again. Obviously this is a bug... anyone else with this issue?