As far as I remember it isn't mentioned anywhere in Valmiki's Ramayan. In certain South East Asian texts (as I'm told) Hanuman isn't shown as a Brahmachari.
Yes in Valmiki Ramayana , there is nothing about his marriage , however in Parashara Samhita (not to be confused with Parashara Smriti) , it is mentioned that Lord Hanuman did marry .
http://www.jayahanumanji.com/?p=2226 see shloka no. 8-9
And do remember it was spiritual marriage , not physical marriage like that of humans