I think its just normal behaviour for a 3 month old. Mines doing the same but I know shes no where near ready for solids. This is around the age that they start to put things into their mouth, thats how they learn. DD constantly has her hands, blankets, toys, my arm/hand... what evers going really.. in her mouth. If I put dip on her hands too it would go straight in her mouth. I think starting solids this early you would be asking for a very unsettled baby as her digestive system wouldnt be ready. She doesnt need it.