Hi I Have Very Hard Calf Muscles At The Back

Hi i have very hard calf muscles at the back of my legs.iv been doing more walking recently than i usto do and was woundering if this could could be why.sometimes i can feel the calf muscles touch each other while doing daily activities which is something my leg muscles havent done befor and this is when i noticed how hard they felt and found it strange.have they got bigger or more toned from walking more.a bit of a strange question really or maybe it could be a really obvious answer.thankyou