Should I be concerned???

[UhhhOhhh]

OMG!

my feeling is you should call your own lawyer's paralegal and make sure he/she understands that this is very important to you and that he/she must get their act together so that your case goes completely smoothly. firmly hint that anything further that goes wrong will trigger your complaining to your lawyer, who is the paralegal's boss. the paralegal would not want to get fired, so i would think they would do things right from here on.

did the trustee's assistant tell you whether the deed was received? if you don't know yet, get on your paralegal's case, make the paralegal call and verify it was received.

i find it strange that the trustee's assistant told you to call them back directly. they should not be initiating direct contact with you if you have a lawyer (like JRScott said). i think your lawyer/paralegal should be the ones to call and follow up. you hired and paid them precisely so you won't have to deal directly with all this.

I would speak with my attorney directly and tell him/her what transpired. You dont have to be angry, but rather just come across in a 'hey.... this could have been really bad' kind of tone.
The reality IS that this could have had a potentially disastrous outcome - all due to the negligence of the paralegal!! Its possible that this paralegal routinely makes careless errors like this, jeapordizing clients cases, but if no one clues the attorney in, he could wind up with a boatload of clients suing him for negligence or what have you.
Just my opinion