Yes, it is normal that after 4-5 years to experience what you are. After all, the diapers are just fabric and any fabric that is washed, say 2-3 times per week, is going to break down. Truly, 5 years is a long life for cloth diapers! Mother Ease are exceptional for long term usage and break down only after multiple kids have been through them, so don't feel let down by the diaper. Most other brands would have bit the dust after 5 years of continual use!
I suggest you buy some of the ME liners (boosters to some) (snap in or not, depending if you have OS or Sandys) for added absorbency if you need it. Hopefully you won't have to buy new diapers if you use a liner.