leg weakness question

mammado11

So I was working out about 5 times a week for about 3 months. But around the first week of July had to go home for a family emergency, so I wasn't able to work out for 3 weeks. So Monday once I was back home I got on the elliptical for 30 minutes, then 40 on Tues. Yesterday I woke up and my legs felt really weak, like I was going to fall over. Not sore, just like jello! Could it be the fact that I took such a long break of working out? Any ideas would be much appreicated! Thanks!