Simple_query_string with first term having a + or - operator

Question regarding the use of AND (+) and NOT (-) operators when using the simple_query_string query.

It seems there is some inconsistent behavior when performing a query where the first term has an operator included in it.
For example: query: +somevalue anothervalue. when using a simple_query_string it seems like the operator is ignored so you get back all results that have either one of these values. If I switched the terms around so the +somevalue is after anothervalue the results are as desired, i.e. show me all results that include anothervalue AND somevalue

When I use the same query using query_string the results are correct regardless of where the and term is.
Is this a bug or is this how the simple_query_string is supposed to interpret the query?