I have not been able to get an erection for the past 4 days, is that an issue for a guy my age?

No: Regardless of your age, guys will always have their ups & downs, pun intended, good days & bad. Think back to what's gone on lately in your life. More stress? Job, money, family, relationship w/your partner? Smoking? Excess alcohol? These can all have an immediate effect on erectile function. Your health can decrease firmness over time. Most likely, you'll have a raging erection the next time.