Is it legal for the maintenance guy at an apartment to take pictures of you without your permission?

My husband and I, His twin and fiancee all live in the same apartment complex. We sometimes will go outside in the evening (after the children are sleeping) and hang out just to have some time with other adults and converse. We smoke, but maintain at least 25 feet between us and the building as is the law. We will chit chat sometimes for an hour or so, but never cause any problems. We are courteous to our neighbors and keep quiet voices (we all have children, so we understand how frustrating it can be when neighbors are loud). Tonight, My BIL's fiancee and I were inside and the guys were outside. During that time, the maintenance guy came out of his apartment, took a picture of them, and then took off and disappeared around the building. I want to know by the Laws of WA state, if that is legal to take pics without permission or knowledge of why he is taking them. Please, mature answers only. Thank you!