Sometimes, actually many times we may witness that a devotee does nice service and feels proud that he or she is close to his/her spiritual master - that he/she is special in the eyes of the spiritual master. Such thinking is not compatible with suddha bhakti.
Srila Bhaktisiddhanta Saraswati Takur Prabhupada had this to say regarding a disciple feeling puffed up and favored by the guru.
"If a student feels favored, he is like a mosquito perched on the lap of a king, thinking 'All these people are my subjects,' but all he can really do is bite the king" - by Srila Bhaktisiddhanta Saraswati Takur
A lesson duly to be noted if we are sincere!