Hell yes, if someone decided to sue you, they could sue you for (ab)use or infringement of trade or service mark even if you gave it away.
Example: 1970's "Cocaine" t-shirts were chased and put down by Coca-Cola because of dilution of and infringement upon their (Coke's) trademark and distinctive script styling used in the "old Coke" logo.
Income isn't the issue. Damage is the issue.
MMB, still not a lawyer