It could be like Kim mentioned, it could be more of "exploration chewing". Babies tend to put things into their mouths because they want to find out what a certain object feels like. They have more nerve endings in their mouth, which can help them figure out the objects around them. Also, they have not developed fine motor kills to help them stroke, or explore the objects. They are likely to continue this form of “exploration” till they are two.
To differentiate between teething and the “exploration” chewing, look out for teething signs such as increased drooling and swollen gums.
For more information on this, you can check out this article: http://www.babycentre.co.uk/x6721/why-does-my-baby-put-everything-in-her-mouth
Hope this helps!