I tried making raspberry jam and packed it in jars, hot and canned. when I opened it for use, the top layer has a good jam-like consistency and texture but when further layers are scooped out they have a more spreadable consistency. it's been long since I used other home made and store bought jams. Could anyone let me know whether this is normal or am I doing something wrong?  The same was the case when I packed the cooled down jam and used it at a later point of time (both refrigerated version and non-refrigerated version). 
In addition to actually adding unwanted species, you're also adding moisture to a food that's otherwise very low in water. This will change its ability to support the growth of mould and bacteria in the damp bits.  If you polish off a jar in a few days and always eat the bit you previously got saliva on, I'm sure the risks will be vanishingly small. If you leave it for a couple of weeks after dipping in a well-licked spoon, I'm less confident.  As a practical measure it would seem easy to spoon out as much as you want into another container, then eat that. That also means you have the option of sharing it rather than having to refuse on the basis that you might as well have spat in it.  