I hate to be a stick-in-the-mud (^_^), but why are these programs offering you pre-matches, in the first place? If the program uses NRMP, then they must follow the guidelines: ie:
"4.2 Exclusive Commitment to the Matching Program
The institution agrees that prior to the release of the results of the Matching Program, all of the programs sponsored by the institution, including those that do not participate in the Matching Program, will select senior students of U.S. allopathic medical schools only through the Matching Program or another national matching plan. If any position is offered to U.S. allopathic students outside the Matching Program or another national matching plan, including a preliminary position for a program that participates in another national matching plan, the institution and the program will be in breach of this Agreement and may suffer the penalties described in Section 9.0."
Exceptions to this would be if you are off-cycle and not going through the match or if you are a PGY2 and changing specialties, etc.
I bring this up because if the program is willing to breach its ethics (and make you vulnerable by placing you in a compromising position), then maybe you should think twice about the program. As a former chief resident - I know that the program directors are fully aware of the rules - and really should know better...
If they like you and you like them - then you will match with them - so what's the problem?