Generally RES only spawn once per year. They generally spawn when water temps hit 70-72 but will spawn for around a month or more after that... I usually see RES on their nests in early to mid May in my area, you'll probably be a bit later than me being further north. What you are describing sounds like spawning behavior for the RES.

LMB spawn about a month earlier than BG/RES when water temps push into the low 60's, generally early April where I am.