Hello haohaoren, and welcome to UKY.
As I understand, RRSPs can come in different flavours, from a simple cash account to more complicated investments. The following is a site where there have been many questions/comments on both the late filing of FBARS for those with Canadian ties, and the dilemma of RRSPs. Although the titles to the threads may differ, have a look at most and you'll discover that many develop into discussions of the above for those with the Canadian tie.
http://www.expatforum.com/expats/expat-tax/Another site that deals strictly with US/Canadian tax concerns is:
http://forums.serbinski.com/viewforum.php?f=2This site is down at times during the day, so if at first you don't find it, try later. This site has many topics concerning Form 8891.
Since you now live in the US, the deadline for filing Form 8938 was April 17th, so yes, if you are required to file it, you are late.
The following IRS chart may be of assistance in determining filing thresholds, assets to be declared, etc.:
http://www.irs.gov/businesses/article/0,,id=255986,00.htmlI take it your main concern is the oversight of your previous preparer to file FBARS. From your comments, it appears you had a US tie prior to moving to the States recently. As to the issue of 'reasonable cause' due to the oversights by the preparer, I'm afraid acceptance of that will be up to the IRS, but you need to prepare the letter of explanation carefully. You might want to seek professional advice from a qualified US/Canadian preparer.