I don't believe so.  As long as you were not turning around and selling that virtual currency to another person in the US in one of the 48 States with Money Transmitter Laws.

In the March 18th "interpretive Guidance" FinCEN defined three categories for persons dealing with virtual currencies:

Users
Exchangers
Issurer

"A user of virtual currency is not an MSB under FinCEN’s regulations and therefore is not subject to MSB registration, reporting, and recordkeeping regulations."

FinCEN’s regulations define “person” as “an individual, a corporation, a partnership, a trust or estate, a joint stock company, an association, a syndicate, joint venture, or other unincorporated organization or group, an Indian Tribe (as that term is defined in the Indian Gaming Regulatory Act), and all entities cognizable as legal personalities.”

"A user is a person that obtains virtual currency to purchase goods or services."

How a person engages in “obtaining” a virtual currency may be described using any number of other terms, such as “earning,” “harvesting,” ”mining,” “creating,” “auto-generating,” “manufacturing,” or “purchasing,” depending on the details of the specific virtual currency model involved. For purposes of this guidance, the label applied to a particular process of obtaining a virtual currency is not material to the legal characterization under the BSA of the process or of the person engaging in the process.

http://fincen.gov/statutes_regs/guidance/pdf/FIN-2013-G001.pdf